On a boat trailer these important points should be considered.
1] The wheel bearings need to be well greased and not in contact with salt water. This causes the bearings to become pitted and corroded. This in turn causes the bearings to overheat and breakdown resulting in a hub failure and another trailer at the side of the road.
2] The brake shoes and activators should move freely and be adjusted for optimum braking. When a new trailer is bought the internal moving parts are not usually protected against the marine environment.
3] Brake cables,called Bowden cables, should move freely but after salt water immersion they soon start to catch and then eventually sieze.
4] The coupling and hand brake needs to be lubricated to keep from seizing up.
5] Rollers ,winches and other moving parts need to be lubricated.
Preventive measures taken early lead to a long trailer life and far less overall cost.
Dont worry though if it seems to have gone to far.
Remember it can all be sorted out !!